Androgens, Estrogens, and Bone in Men

• Bone density
• Androgens
• Estrogens
• Testosterone
• Estradiol

It is well established that serum testosterone levels decrease as men age. Bone mineral density decreases with age in both women and men, and 30% of all hip fractures occur in men. The possibility that these two observations are linked and that replacement of androgens in older androgen-deficient men will have positive effects on bone has considerable medical and economic importance.

In this issue, Amin and colleagues (1) report a lack of relationship between serum levels of total testosterone and bone mineral density in a well-established and often-studied population of older men. However, they found a strong positive correlation between serum estradiol level and bone mineral density. These data are of considerable interest and require careful interpretation because they may have implications for management of older men by using androgen replacement treatment. In this editorial, we attempt to place the issue in perspective.

Hypogonadism in younger men is associated with increased risk for osteopenia (2-5). It has therefore been assumed that low serum levels of testosterone lead to osteopenia and may be responsible in part for osteoporosis and minimal trauma fractures in older men. This concept is supported by numerous studies showing that long-term testosterone replacement in young and older men with hypogonadism increased bone mineral density (6-11). Until recently, most of the controversy about androgens and bone mineral density has focused …